Index

Sleep after Learning and Sharp your Memory

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We spend almost a third of our life sleeping. Good quality sleep is essential for good health and well-being. However, lifestyle and environmental factors are increasingly causing difficulties in sleeping.Sleep is a basic human need and is essential for good health, good quality of life and performing well during the day. Several indicators can be used to describe sleep disturbance or sleep disorders.

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On average, adults cycle through all forms of sleep every 90 minutes. Therefore if a person sleeps for 8 hours, he or she will have 5 opportunities to repair both the physical and psychological systems. Eight hours is the average length of time that adults sleep.Natural sleep is best. It's physically restorative, and it usually provides enough dreaming time (REM sleep) to improve learning, memory and mood.

Each 90-minute cycle serves a unique function. When a person first falls asleep, the bulk of those 90 minutes is spent in physical repair with only a small percentage dedicated to psychological repair. As the night wears on, the balance shifts so that in the morning, just before awakening, very little time is spent in physical repair with the bulk of sleep time being dedicated to psychological repair. While we do have some dreaming every 90 minutes, we have much more of it near morning. Thus we are more likely to remember dreaming if we awaken during a cycle that is dominated by dreaming.

Children's health and behavior take a nose dive when their sleep habits are out of whack. Insufficient sleep makes children short-tempered and whiny. In school, a sleep-deprived child has trouble with concentration, memory, physical performance and decision making.On the flip side, adequate sleep will boost your child's energy and enthusiasm. Good-quality sleep also can help your child learn more easily and reduce many behavioral problems.

The main effects of sleep deprivation include physical effects (sleepiness, fatigue, hypertension) cognitive impairment (deterioration of performance, attention and motivation; diminishment of mental concentration and intellectual capacity and increase of the likelihood of accidents at work and during driving) and mental health complications. Inadequate rest impairs the ability to think, to handle stress, to maintain a healthy immune system, and to moderate emotions.

These changes eventually make it hard for people who have dementia to care for themselves. Dementia may also cause changes in mood and personality. Early on, lapses in memory and clear thinking may bother the person with dementia. Later, disruptive behavior and other problems can create a burden for caregivers and other family members.

Popular sayings such as "sleep on it" or "consult the pillow" reflect the notion that remolded memories produce new creative associations in the morning, and that often performance improves after a time-interval that included sleep. Many studies demonstrate that a healthy sleep produces a significant learning dependent performance boost. Healthy sleep must include the appropriate sequence and proportion of NREM and REM phases, which play a different role in memory consolidation-optimization process. In motor skill learning, an interval of sleep may be critical for the expression of performance gains; without sleep these gains will be delayed (Korman et al, 2003).

Persons who are depressed may not find the motivation to work in rehabilitation. They feel discouraged and hopeless. They may feel fatigued,difficulty concentrating, remembering, making decisions,insomnia, early-morning awakening, sleep poorly and don’t eat well.

Sleep is very important, especially for children. Children who get enough sleep are less likely to have behavior problems and moodiness. They often develop better memory, concentration, and longer attention spans. With plenty of sleep, they may also recover from illness faster.

If sleep is disrupted over a long period of time, necessary physiological and psychological repair cannot take place, which can lead to pain, fatigue, and memory and thinking difficulty. Additional consequences of poor sleep may include difficulty maintaining alertness, lack of energy, impaired mood, and trouble handling stress. The day after a night of abnormal or poor sleep is, whatever the cause, a disturbed day. People can fall asleep at work, at school or when driving; feel tired; have concentration and vigilance detriments; have memory blanks; irritability; frustration; and have a higher probability of accidents or injury.

Researchers found that sleep not only protects memories from outside interferences, it also helps strengthen them.

"There was a very large benefit of sleep for memory consolidation, even larger than we were anticipating," said study author Dr. Jeffrey Ellenbogen, an associate neurologist at Brigham and Women's Hospital, Boston, and a postdoctoral fellow in sleep medicine at Harvard Medical School.

The research is scheduled to be presented May 2 at the American Academy of Neurology annual meeting in Boston.

In the study, the researchers focused on sleep's impact on "declarative" memories, which are related to specific facts, episodes and events.

"We sought to explore whether sleep has any impact on memory consolidation, specifically the type of memory for facts and events and time," Ellenbogen said. "We know that sleep helps boost memory for procedural tests, such as learning a new piano sequence, but we're not sure, even though it's been debated for 100 years, whether sleep impacts declarative memory."

The study involved 48 people between the ages of 18 and 30. These participants had normal, healthy sleep routines and were not taking any medications. They were all taught 20 pairs of words and asked to recall them 12 hours later. However, the participants were divided evenly into four groups with different circumstances for testing: sleep before testing, wake before testing, sleep before testing with interference, or wake before testing with interference.

Two of the groups (the wake groups) were taught the words at 9 a.m. and then tested on the pairings at 9 p.m., after being awake all day. The other two groups (the sleep groups) learned the words at 9 p.m., went to sleep, and were then tested at 9 a.m.

Also, prior to testing, one of the sleep groups and one of the wake groups were given a second list of 20 word pairs to remember. These groups were then tested on both lists to help determine memory recall with interference (competing information).

The result: Sleep appeared to help particpants recall their learned declarative memories, even when they were given competing information.

According to the researchers, people who slept after learning the information performed best, successfully recalling more words whether or not there was interference. Those in the sleep group without interference were able to recall 12 percent more word pairings from the first list than the wake group without interference (94 percent recall for the sleep group vs. 82 percent for the wake group).

When presented with interference, those who slept before testing did significantly better at remembering the words (76 percent for the sleep group vs. 32 percent for the wake group).

"We were surprised to find the order of magnitude by which the data demonstrated our effects," Ellenbogen said.

Jan Born, a professor of neuroendocrinology at the University of Lübeck in Germany, said the study offers more proof of the importance of sleep for memory consolidation.

"Considering that learning in every educational setting (schools, colleges, etc.), is centrally based on hippocampus-dependent memory function [declarative memories], people should realize that optimal learning conditions require proper sleep," he said.

Proper sleep may have other benefits, too, added Michael Perlis, director of the Sleep Research Laboratory at the University of Rochester in Rochester, NY. Research has shown that in addition to memory, sleep may be related to physical functioning, good immune function, physical and cognitive performance, and mood regulation, he said.

"These are all theories. The only thing we know is that when we're deprived of sleep, we do less well. Is that a lack of sleep or sustained wakefulness? It's very difficult to figure out how to crack that nut," he said. "We spend 30 percent of our time on sleep. What is sleep for? This is a riddle we're still working on."